<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="div">
        <!-- v-if:格式为 v-if="条件" -->
        <div v-if="age>=90">年龄大于90</div>
        <div v-else-if="age>=60">年龄大于60</div>
        <div v-else-if="age>=30">年龄大于30</div>
        <div v-else>年龄小于30</div>
    </div>
</body>
<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script>
    const app = new Vue({
        el: '#div',
        data: {
            age: 50
        },
    })
</script>

</html>